Bruce I am going to build integral FRP water and diesel tanks into my '67 Islander 33. Is 105 resin suitable for the inside finish of a potable water tank? a diesel tank? What is the best method for attaching the tops? Thanks Ron
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Potable water tanks
It's important that you know we do not have any NSF or FDA approval for any of our systems. The reason is that there is no way for us to control how it's used - or more importantly misued - out in the world. But, that said, many people have built potable water tanks with our products and have had no ill effects. If properly mixed epoxy cures to an inert plastic solid and shouldn't pose a health risk. The following text is from an article published in Epoxyworks magazine as it pertains to a potable water tank: 1) Coat all interior surfaces with 5 or 6 coats of rolled epoxy. The inside of the tank should be treated similar to the outside of a hull. We recommend a minimum of 20-mil coverage, which is five or six rolled coats of epoxy, for all interior surfaces of tanks. This is similar to the coverage recommended as a “barrier coat” for the exterior of a hull. After it is rolled on, brush the epoxy out to minimize any entrapped air. Install surge baffles to minimize free surface effect, using generous fillets and giving them the same 5-6 coats of epoxy as the rest of the tank interior. Any tank openings, such as fill, vent, inspection or clean out, should be oversized and also receive 5-6 coats of epoxy. We recommend that fasteners be epoxy bonded in place to secure any hardware to the tank or in the construction of the tank (See details of hardware bonding in the WEST SYSTEM User Manual & Product Guide.) 2) Use a slightly resin-rich/ hardener-lean epoxy mixture. Carefully metered resin/hardener ratio is critical to any epoxy’s performance. In all projects, with one exception, we recommend dispensing and mixing epoxy at the target ratio within our acceptable range. Tank building is the exception to the rule. When mixing epoxy for tank coatings, we recommend a resin-rich/ hardener-lean mixture at the outer limits of the acceptable range as follows: This is because excess resin in epoxy is less likely to adversely affect the physical properties of cured epoxy than excess hardener. When excess hardener is in the epoxy matrix, it cannot fully react with the resin and will become suspended in the mixture. Because amines (in the hardeners) are water soluble, they can potentially leach out and cause odd tastes, contaminates in the liquid, and porosity in the epoxy film, among other performance defects. The maximum resin-rich ratios noted below are at the end of acceptable ranges for WEST SYSTEM epoxy. These ratios should not be taken any farther from the target. These maximum resin-rich ratios meet specification to obtain a properly cured epoxy film and to minimize extracts leaching out of the epoxy. When using 300 Mini Pumps, one way to obtain the resin-rich/hardener-lean ratio within the acceptable range is to dispense the following: 105 Resin + 207 Hardener Pumps Resin Pumps Hardener 7 6 (Note: Use the 207 hardener for the potable water tank using this technique. For the diesel tank you can use any resin/hardener combination using equal pumps - it doesn't need to be hardener lean.) 3) Mix thoroughly, using a double-pot method. We recommend using a double-pot mixing method when building or coating tanks. Completely thorough mixing of epoxy is difficult to achieve when resin and hardener are pumped and mixed in one container. A film of resin or hardener will cling to the bottom or side of the container leaving areas of unmixed or undermixed components. This can be readily seen when tinted epoxy is mixed together. To ensure thorough mixing, first dispense and mix resin and hardener in one container, carefully scraping the sides and bottom. Scraping is key because it incorporates the majority of the single components into the mixture. Second, transfer this mixed epoxy into another clean mixing container. Use a new stir stick to mix a second time. This transfer will eliminate any clinging unmixed material and additional mixing will assure thorough crosslinking of both components.
It's important that you know we do not have any NSF or FDA approval for any of our systems. The reason is that there is no way for us to control how it's used - or more importantly misued - out in the world. But, that said, many people have built potable water tanks with our products and have had no ill effects. If properly mixed epoxy cures to an inert plastic solid and shouldn't pose a health risk. The following text is from an article published in Epoxyworks magazine as it pertains to a potable water tank: 1) Coat all interior surfaces with 5 or 6 coats of rolled epoxy. The inside of the tank should be treated similar to the outside of a hull. We recommend a minimum of 20-mil coverage, which is five or six rolled coats of epoxy, for all interior surfaces of tanks. This is similar to the coverage recommended as a “barrier coat” for the exterior of a hull. After it is rolled on, brush the epoxy out to minimize any entrapped air. Install surge baffles to minimize free surface effect, using generous fillets and giving them the same 5-6 coats of epoxy as the rest of the tank interior. Any tank openings, such as fill, vent, inspection or clean out, should be oversized and also receive 5-6 coats of epoxy. We recommend that fasteners be epoxy bonded in place to secure any hardware to the tank or in the construction of the tank (See details of hardware bonding in the WEST SYSTEM User Manual & Product Guide.) 2) Use a slightly resin-rich/ hardener-lean epoxy mixture. Carefully metered resin/hardener ratio is critical to any epoxy’s performance. In all projects, with one exception, we recommend dispensing and mixing epoxy at the target ratio within our acceptable range. Tank building is the exception to the rule. When mixing epoxy for tank coatings, we recommend a resin-rich/ hardener-lean mixture at the outer limits of the acceptable range as follows: This is because excess resin in epoxy is less likely to adversely affect the physical properties of cured epoxy than excess hardener. When excess hardener is in the epoxy matrix, it cannot fully react with the resin and will become suspended in the mixture. Because amines (in the hardeners) are water soluble, they can potentially leach out and cause odd tastes, contaminates in the liquid, and porosity in the epoxy film, among other performance defects. The maximum resin-rich ratios noted below are at the end of acceptable ranges for WEST SYSTEM epoxy. These ratios should not be taken any farther from the target. These maximum resin-rich ratios meet specification to obtain a properly cured epoxy film and to minimize extracts leaching out of the epoxy. When using 300 Mini Pumps, one way to obtain the resin-rich/hardener-lean ratio within the acceptable range is to dispense the following: 105 Resin + 207 Hardener Pumps Resin Pumps Hardener 7 6 (Note: Use the 207 hardener for the potable water tank using this technique. For the diesel tank you can use any resin/hardener combination using equal pumps - it doesn't need to be hardener lean.) 3) Mix thoroughly, using a double-pot method. We recommend using a double-pot mixing method when building or coating tanks. Completely thorough mixing of epoxy is difficult to achieve when resin and hardener are pumped and mixed in one container. A film of resin or hardener will cling to the bottom or side of the container leaving areas of unmixed or undermixed components. This can be readily seen when tinted epoxy is mixed together. To ensure thorough mixing, first dispense and mix resin and hardener in one container, carefully scraping the sides and bottom. Scraping is key because it incorporates the majority of the single components into the mixture. Second, transfer this mixed epoxy into another clean mixing container. Use a new stir stick to mix a second time. This transfer will eliminate any clinging unmixed material and additional mixing will assure thorough crosslinking of both components.
Just my $.02 worth re integral tankage, Ron
I'm not a fan of 'em--especially not integral fuel or waste tanks (I know you're thinking potable water)...'cuz they tend to eliminate that area for ANY other future use...even water tanks if any wall is structural. Plus, even water tanks can be subject to the same problems--moisture intrusion, rot etc--that any other inegral part of the hull can be...but because it happens from the inside of the tank, is almost always unnoticed till the problem has become really serious. Boats last for decades--maybe even centuries...no one knows yet what the max lifespan of a fiberglass hull is. Times change, and with them so does technology...and so do owners...and all of those things create changing needs for various areas of a boat. So if you want to build a fiberglass tank and drop it in, you'd get no argument from me (although it would easier and just about as inexpensive to drop in a good quality plastic tank)...but IMO all tankage--and just about everything else possible on a boat) should be removeable. As I said...just my $.02 worth on the subject.
I'm not a fan of 'em--especially not integral fuel or waste tanks (I know you're thinking potable water)...'cuz they tend to eliminate that area for ANY other future use...even water tanks if any wall is structural. Plus, even water tanks can be subject to the same problems--moisture intrusion, rot etc--that any other inegral part of the hull can be...but because it happens from the inside of the tank, is almost always unnoticed till the problem has become really serious. Boats last for decades--maybe even centuries...no one knows yet what the max lifespan of a fiberglass hull is. Times change, and with them so does technology...and so do owners...and all of those things create changing needs for various areas of a boat. So if you want to build a fiberglass tank and drop it in, you'd get no argument from me (although it would easier and just about as inexpensive to drop in a good quality plastic tank)...but IMO all tankage--and just about everything else possible on a boat) should be removeable. As I said...just my $.02 worth on the subject.
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